1. Field of the Invention
The invention relates essentially to a device for providing improved electrical contact between an electrical conductor and an electrode, the use of said device in any device for advancing an electrode, and the incorporation of said device for providing electrical contact in an apparatus for generating shock waves or high frequency pulses.
2. Prior Art
Apparatus for generating shock waves or high frequency pulses, among then "lithotriptors", have been known for many years. Such apparatus include a device for focusing pulses on a target and may be constituted, in particular, by a truncated elliptical reflector as described in U.S. Pat. No. 2,559,227 (Rieber).
A similar apparatus is described in patent document FR-A-2 247 195 and U.S. Pat. No. 3,942,531.
The pulses or shock waves are generated by an electric arc or discharge between two electrodes which may be made of a highly conductive material such as copper or brass, and which are mounted on insulating supports.
In general, the discharges generated at the electrodes are accompanied by metal being torn away therefrom, thereby causing the electrodes to wear rapidly, which means that they need replacing relatively frequently.
In order to counter this wear, proposals have already been made in patent document EP-A-124 682 and commonly assigned U.S. Pat. No. 4,608,983 for a device which advances electrodes, said device including a control member which controls simultaneous movement of the electrodes towards or away from each other by means of rotation in one direction or in the opposite direction.
Other electrode-advancing devices are described in commonly assigned U.S. Pat. No. 4,370,614.
U.S. Pat. No. 4,780,614 describes a device for advancing an electrode in which the supply of electrical current from a current source is provided by a conductor which terminates in an electrically conductive element which presses permanently in slidable manner against the electrode-carrier element which is likewise electrically conductive, thereby providing a sliding electrical contact.
However, the present inventors have observed that such a design of an electrical contact complicates assembling and disassembling electrode-carrier elements and their electrodes.
In addition, by virtue of the sliding electrical contact, surface oxidation of the respective sliding contact surfaces may take place, thereby reducing electrical conductivity, and this surface oxidation effect increases when the sliding contact occurs close to the heads of the electrodes. Electrical conductivity may also be reduced if the electrodes become dirty through electrode displacement, either because of the lubricant used, or else because of liquid coming from the liquid-filled cavity in which at least a portion of each electrode is immersed.
Thus, one aim of the invention is to solve a new technical problem consisting in providing a device capable of ensuring improved electrical contact between an electrical conductor for feeding electrical current and an electrode, which device is of simple design and facilitates assembly and disassembly of the the electrode-carrier elements and their electrodes.
Another aim of the present invention is to solve a novel technical problem consisting in providing a device to insure improved electrical contact and which automatically cleans the electrical contact surfaces, thereby giving rise to electrical conductivity which is maintained substantially perfectly at the electrical contact.
Another aim of the invention is to solve a novel technical problem consisting in providing a solution for avoiding the dirtying of the electrical contact by a lubricant or by a liquid coming from a liquid-filled cavity in which at least a portion of the electrode and/or its electrode-carrier element is immersed.
Preferably, these novel technical problems should be solved in such a manner as to be useable in any device for advancing an electrode, and in particular in a device for advancing electrodes constituting a portion of an apparatus for generating shock waves or high frequency pulses, thereby making it possible to increase the effectiveness with which targets such as lithiases or living tissues are destroyed.
These novel technical problems are solved for the first time in satisfactory manner by the present invention by providing a solution of relatively low cost which is largely compensated by a significant improvement in productivity; by an improvement in electrical conductivity during multiple utilizations of the electrodes; and finally by an increase in the effectiveness of target destruction when used in apparatus intended for destroying targets by generating electric arcs or discharges.